JP2015174572A - Optical axis control device for vehicular headlamp and vehicular headlamp system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance accuracy of optical axis control in auto-leveling control using a low cost distance sensor.SOLUTION: An optical axis control device for a headlamp 13 provided in a vehicle having a first portion in which inclination with respect to a road surface fluctuates and a second portion in which the inclination with respect to the road surface hardly fluctuates includes: a distance detection unit 11 mounted in a predetermined position of the first portion of the vehicle and for detecting a distance with a predetermined position of the second portion of the vehicle; a vehicle body inclination angle determination unit 21 for acquiring an inclination angle with respect to a road surface in a front and back direction in the first portion of the vehicle by using the distance detected by the distance detection unit 11; an optical axis control amount setting unit 22 for acquiring an optical axis control amount of the headlamp based on the inclination angle acquired from the vehicle body inclination angle determination unit 21; and an optical axis control signal generating unit 23 for generating a control signal for controlling the optical axis of the headlamp based on the optical axis control amount acquired by the optical axis control amount setting unit 22.

Description

  The present invention relates to a technique for controlling the optical axis of a vehicle headlamp.

  In order to avoid dazzling oncoming vehicles and preceding vehicles, automatic leveling control is known that controls the light irradiation direction of the headlight of the host vehicle, that is, the optical axis in the vertical direction, according to the inclination of the host vehicle with respect to the road surface. ing. For example, the height between the wheel shaft and the body of the host vehicle is detected by a height sensor, the tilt angle in the front-rear direction of the host vehicle is obtained based on the detected value, and the optical axis of the headlamp is calculated based on the tilt angle. By controlling the above, the above automatic leveling control is realized. In recent years, it has been proposed to use a lower-cost distance sensor instead of the height sensor to determine the inclination angle of the host vehicle with respect to the road surface (see, for example, Patent Documents 1 and 2).

  However, the automatic leveling control using the distance sensor has a disadvantage that the accuracy of the optical axis control is lowered because the measurement accuracy of the distance between the traveling vehicle and the road surface is not always sufficient. In addition to the fact that the road surface condition changes and is not stable, in principle, it is necessary to install the distance sensor so as to face the road surface directly. This is due to instability. For this, it is conceivable to increase the distance measurement accuracy by using a high-performance distance sensor that is not easily affected by road surface conditions, etc., but in this case, the intended cost reduction is hindered. The inconvenience arises. As another countermeasure, it may be possible to change the control algorithm so that the optical axis control is performed in consideration of the low detection accuracy of the distance, but in this case, it is difficult to increase the accuracy of the optical axis control. Arise.

JP 2001-260777 A JP 2009-270918 A

  A specific aspect of the present invention is to provide a technique capable of increasing the accuracy of optical axis control in auto leveling control using a low-cost distance sensor.

  An optical axis control device for a vehicle headlamp according to an aspect of the present invention is provided in a vehicle having (a) a first portion whose inclination with respect to a road surface varies and a second portion whose inclination with respect to the road surface does not substantially vary. An apparatus for controlling an optical axis of a headlamp, wherein (b) a distance between a predetermined position of the first part of the vehicle and a predetermined position of the second part of the vehicle is detected. (C) a vehicle body inclination angle determination unit that obtains an inclination angle of the first portion of the vehicle with respect to the road surface in the front-rear direction using the distance detected by the distance detection unit; An optical axis control amount setting unit for obtaining an optical axis control amount of the headlamp based on the inclination angle obtained by the vehicle body inclination angle determination unit; and (e) the light obtained by the optical axis control amount setting unit. The optical axis of the headlamp based on the axis control amount Including the optical axis control signal generator for generating a control signal for controlling an optical axis control unit for headlight for a vehicle.

  According to the above configuration, the distance detection unit is installed at a predetermined position (for example, a headlight installed on the body) of the first part of the vehicle, and the predetermined position (for example, the second part of the vehicle by the distance detection unit) The inclination angle can be obtained by detecting the distance to the engine surface), and the optical axis can be controlled accordingly. Since the portion inside the vehicle is the measurement target without setting the road surface as the measurement target, the distance can be detected stably without being affected by the disturbance. In addition, since the part inside the vehicle is used, the shape of the part to be measured is known, so that the accuracy of distance detection can be improved by taking this into consideration. Therefore, the accuracy of optical axis control can be increased.

  In the above-described optical axis control device, the distance detection unit includes two distance sensors that are spaced apart from each other in the vertical direction, and the distance between each of the distance sensors and a predetermined position of the second part of the vehicle is It is preferable that the vehicle body inclination angle determination unit obtains the inclination angle by using two distances detected by the two distance sensors. Further, in this case, the two distance sensors are arranged so that the distance detection direction of the other distance sensor is non-parallel with a predetermined angle with respect to the distance detection direction of the one distance sensor. It is more preferable that the other distance sensor is inclined relative to the other.

  By using each distance detected by each of the two distance sensors, for example, a predetermined calculation is performed, or a combination of each distance value is referred to in a data table prepared in advance. it can. In addition, by arranging the distance sensors to be relatively inclined, it is possible to increase the amount of change in the detected distances, and thus it is possible to improve the detection accuracy of the inclination angle.

  In the optical axis control device, the distance detection unit includes one distance sensor, and the distance sensor detects a distance from the predetermined position of the second part of the vehicle, and the vehicle body inclination angle It is also preferable that the determination unit obtains the tilt angle using a distance detected by the distance sensor and a predetermined fixed value distance.

  Thereby, only one distance sensor is required, and the configuration can be simplified and the cost can be reduced.

  A vehicle headlamp system according to an aspect of the present invention includes any one of the optical axis control devices described above and a headlamp whose optical axis is controlled by the optical axis control device. It is.

  This provides a vehicle headlamp system that can improve the accuracy of optical axis control in auto-leveling control using a low-cost distance sensor.

FIG. 1 is a diagram schematically showing the structure of a vehicle. FIG. 2 is a block diagram showing the overall configuration of the vehicle headlamp system. FIG. 3 is a principle diagram for explaining a method of obtaining the inclination angle of the vehicle body with respect to the road surface. FIG. 4 is a diagram illustrating the relationship between the measurement target surface and each distance detected by the distance sensor. FIG. 5 is a diagram showing an arrangement in which each distance sensor is installed separately on the left and right. FIG. 4 is a diagram illustrating the relationship between the measurement target surface and each distance detected by the distance sensor.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram schematically showing the structure of a vehicle. In general, the components of the vehicle 100 are roughly divided into a body (vehicle body) 101 and a power system (chassis) 102 (see FIG. 1A). The body 101 includes a passenger compartment for a driver or the like inside, and a headlight is attached to the front and a taillight is attached to the rear. The power system 102 is related to the operation of the vehicle 100, and specifically includes an engine 103, a drive shaft and wheels that transmit the driving force thereof, and the like. And compared with the vehicle 100 (refer FIG. 1 (B)) at the time of normal driving | running | working, for example at the time of acceleration, it will be in the state which the front of the body 101 rose relatively. At this time, since the drive system 102 including the engine 103 does not move up and down and moves in the same manner as the road surface, the drive system 102 does not tilt with respect to the road surface, and only the body 101 is tilted with respect to the road surface. (See FIG. 1C).

  Therefore, considering the case where the distance between the predetermined position of the body 101 and the engine 103 included in the drive system 102 or a structure such as a tire, an axle, or a damper is measured, the detected distance depends on the tilt angle of the body 101. Will change. Therefore, the tilt angle of the body 101 can be obtained based on the detected change in distance. In the following embodiment, as an example, the inclination angle of the body 101 is obtained by detecting the distance from the predetermined position of the headlamp provided in the body 101 to the engine 103 of the drive system 102, and based on this inclination angle. The optical axis of the headlamp will be adjusted.

  FIG. 2 is a block diagram illustrating an overall configuration of the vehicle headlamp system according to the embodiment. The vehicle headlamp system shown in FIG. 2 includes a control unit 10, a distance detection unit 11, a memory 12, and a headlamp 13. This vehicle headlamp system is provided in a vehicle having a body (first portion) 101 whose inclination with respect to the road surface varies and a drive system (second portion) 102 where the inclination with respect to the road surface hardly varies. The optical axis control of the headlamp 13 is performed according to the tilt angle of the 101 in the front-rear direction.

  The control unit 10 is realized, for example, by executing a predetermined operation program in a computer system having a CPU, a ROM, a RAM, and the like, and controls the overall operation of the vehicle headlamp system. The control unit 10 includes a vehicle body tilt angle determination unit 21, an optical axis control amount setting unit 22, and an optical axis control signal generation unit 23 as functional blocks.

  The distance detection unit 11 is attached to a predetermined position of the vehicle body 101 and detects a distance from the predetermined position of the drive system 102 of the vehicle. In the present embodiment, the distance detection unit 11 is disposed inside or outside the left or right headlamp 13 and detects a distance from a predetermined position of the engine 103 included in the drive system 102. As will be described in detail later, the distance detection unit 11 of the present embodiment includes two distance sensors 11A and 11B.

  The memory 12 is connected to the control unit 11 and is used for temporary storage in the calculation of the control unit 11. The memory 12 stores data necessary for the calculation of the control unit 11.

  The headlamps 13 are provided at respective left and right predetermined positions in the front portion of the vehicle body 101 and emit light that illuminates the front of the vehicle. The headlamp 13 is provided with an actuator (not shown) and the like, and the direction of the optical axis is controlled in accordance with a control signal from the control unit 10.

  The vehicle body inclination angle determination unit 21 obtains an inclination angle of the body 101 with respect to the road surface based on the distances detected by the distance sensors 11A and 11B of the distance detection unit 11.

  The optical axis control amount setting unit 22 obtains an optical axis control amount indicating how much the optical axis of the headlamp 13 is changed based on the inclination angle of the body 101 obtained by the vehicle body inclination angle determination unit 21.

  The optical axis control signal generation unit 23 generates a control signal for controlling the optical axis of the headlamp 13 based on the optical axis control amount obtained by the optical axis control amount setting unit, and outputs the control signal to the headlamp 13. .

  FIG. 3 is a principle diagram for explaining a method of obtaining the inclination angle of the vehicle body with respect to the road surface. FIG. 3A shows the positional relationship between the distance sensors 11A and 11B and the measurement target surface 104 of the engine 103 when the tilt angle of the body 101 is 0 °. Here, it is assumed that the distance a between the distance sensor 11A and the measurement target surface 104 is a1, and the distance b between the distance sensor 11B and the measurement target surface 104 is b1. The distances a1 and b1 are detected by the distance sensors 11A and 11B. FIG. 3B shows the distance sensors 11A and 11B and the measurement target surface 104 of the engine 103 when the front portion of the body 101 is relatively raised and the tilt angle of the body 101 is a positive value. The positional relationship is shown.

  In this case, it is assumed that the distance a between the distance sensor 11A and the measurement target surface 104 is a2, and the distance b between the distance sensor 11B and the measurement target surface 104 is b2. The distances a2 and b2 are detected by the distance sensors 11A and 11B. Since each distance sensor 11A, 11b is provided at a predetermined position of the body 101, each of the distance sensors 11A and 11b is inclined as shown in FIG. Since an engine 103 does not tilt, the measurement target surface 104 does not tilt. Therefore, the distances a1 and b1 when the tilt angle of the body 101 shown in FIG. 3A is 0 °, and the distance a2 when the tilt angle shown in FIG. 3B is a positive value larger than 0 °. , B2 is a different value. Therefore, the tilt angle θ2 of the body 101 can be obtained using the amount of change in each distance a and b.

  As shown in FIGS. 3A and 3B, the other distance sensor 11B is inclined with respect to one distance sensor 11A, and the distance sensor 11A is used as a reference for the distance detection direction. The detection direction of the distance by 11B is not parallel to this, but has a predetermined mounting angle θ1 (> 0 °). Thereby, since the variation | change_quantity of each distance a and b can be enlarged more, the resolution of angle detection can be enlarged more.

  Next, some specific examples of the method for obtaining the tilt angle θ2 of the body 101 using the variation amounts of the distances a and b will be described.

For example, assuming that the tilt angle is 0 °, the difference between the distances a1 and b1 in this case is (b1−a1) [mm]. If the difference between the distances a2 and b2 when the tilt angle is a positive value larger than 0 ° is (b2−a2) [mm], the tilt angle θ2 can be expressed as follows.
θ2 = ((b2−a2) − (b1−a1)) × K1 [deg]

  Here, the coefficient K1 [deg / mm] is a coefficient obtained by previously obtaining the magnitude of the tilt angle per 1 mm difference from the relationship between the difference between (b2-a2) and (b1-a1) and the magnitude of the tilt angle. is there. The vehicle body tilt angle determination unit 21 can determine the tilt angle θ2 of the body 101 based on the above calculation formula using the distances detected by the distance sensors 11A and 11B of the distance detection unit 11. According to this calculation formula, when the entire body 101 simply moves up and down, the distances a and b do not change, so the tilt angle θ2 does not change. That is, it is possible to identify simple vertical movement of the body 101 and inclination in the front-rear direction.

As another method, the relationship between each distance between the measurement target surface 104 and each distance sensor 11A, 11B and the inclination angle θ2 is obtained in advance, and this is stored in the memory 12 as a data table. The inclination angle θ2 can also be obtained by referring to it. As an example, an example of a data table in the case where the measurement target surface 104 is a flat surface as shown in FIG. The vehicle body tilt angle determination unit 21 can determine the tilt angle by reading the tilt angle corresponding to the combination of the distances detected by the distance sensors 11A and 11B from the data table. Even in the method using this data table, when the entire body 101 simply moves up and down, the distances a and b do not change, and therefore the inclination angle θ2 does not change. That is, it is possible to identify simple vertical movement of the body 101 and inclination in the front-rear direction.

Note that a flat surface is ideal for the measurement target surface 104, but in the case of an object whose surface shape is known in advance, such as the engine 103, a data table is prepared taking into account information about the shape. Just keep it. For example, as shown in FIG. 4B, the measurement target surface 104 is stepped in the middle, and the distance b (b1, b2,...) Detected by the distance sensor 11B decreases from an increase in the middle. An example of the data table in the case of turning to is shown below. Even in the case where the measurement target surface 104 has an arbitrary shape that is not a flat surface as in this case, the inclination angle can be determined by preparing the inclination angle corresponding to each combination of distances as a data table. .

  FIG. 5 is a schematic diagram for explaining another installation example of the distance sensor. In the above description, each distance sensor 11A, 11B is installed in association with one headlamp 13, but one distance sensor 11A, 11B is associated with each left and right headlamp 13. May be installed. In the example shown in the figure, a distance sensor 11A is provided in association with the right headlight 13, and the distance sensor 11A measures the distance a between the measurement target surface 104 located on the right side of the engine 103 and the left side. A distance sensor 11B is provided in association with the headlamp 13, and the distance b between the measurement target surface 104 located on the left side of the engine 103 is measured by the distance sensor 11B.

  In the case where the distance sensors 11A and 11B are installed separately on the left and right as shown in FIG. 5, the distances between the distance sensors 11A and 11B and the measurement target surfaces 104 are set to be the same in parallel. When the measurement target surface 104 is a flat surface within the measurement range, the inclination angle of the body 101 is determined by the following method using the distances a and b detected by the distance sensors 11A and 11B. You can ask for it. This will be described with reference to FIG. Here, for convenience of explanation, it is assumed that the measurement target surface 104 is inclined with respect to the vertical direction, and the distance sensors 11A and 11B are arranged vertically along the vertical direction.

  When the entire body 101 moves up and down, as shown in FIG. 6A, the relative positional relationship between the distance sensors 11A and 11B and the measurement target surface 104 indicates the positions of the distance sensors 11A and the like. When fixed and considered relatively, the position of the measurement target surface 104 changes up and down. At this time, the distance detected by the distance sensor 11A at the reference position is a, and the distance detected by the distance sensor 11A when the position of the measurement target surface 104 changes up and down is a1. Similarly, the distance detected by the distance sensor 11B at the reference position is b, and the distance detected by the distance sensor 11B when the position of the measurement target surface 104 changes up and down is b1. When the entire body 101 moves up and down, that is, when the tilt angle of the body 101 does not change, the ratio a / b between the distance a and the distance b and the ratio a1 / b1 between the distance a1 and the distance b1 are equal ( That is, a / b = a1 / b1).

When the body 101 tilts in the front-rear direction, as shown in FIG. 6B, the relative positional relationship between the distance sensors 11A and 11B and the measurement target surface 104 indicates the position of each distance sensor 11A and the like. When fixed and relatively considered, the measurement target surface 104 changes clockwise or counterclockwise. When the body 101 tilts in the front-rear direction, that is, when the tilt angle of the body 101 changes, the ratio a / b between the distance a and the distance b and the ratio a1 / b1 between the distance a1 and the distance b1 are not equal ( That is, a / b ≠ a1 / b1). Specifically, when a / b> a1 / b1, the body 101 is tilted in the direction in which the optical axis of the headlamp 13 is lowered. When a / b <a1 / b1, the light of the headlamp 13 is indicated. It shows that the body 101 is inclined in the direction in which the axis rises. Since the ratio a / b between the distance a and the distance b is constant, for example, if the relationship between the ratio a1 / b1 between the distance a1 and the distance b1 and the tilt angle is obtained in advance and used as a data table, this data table is referred to. The inclination angle θ2 can also be determined. A specific example of the data table is shown below.

  In addition to the distance sensors 11A and 11B described above, the third distance sensor can be used to detect the tilt of the body 101 in the left-right direction, and the tilt angle in the front-rear direction of the body 101 can be more accurately determined. Can be calculated. When a tilt in the left-right direction occurs and a tilt in the front-rear direction also occurs, a data table of combinations of distances detected by each distance sensor is obtained in advance and stored in the memory 12 to An inclination angle can be determined in consideration of the inclination of the direction. Moreover, since the inclination in the left-right direction is obtained, the optical axes of the left and right headlamps 13 can be individually controlled.

  According to the embodiment as described above, since a part inside the vehicle is set as a measurement target without setting the road surface as a measurement target, the distance can be stably detected without being affected by the disturbance. In addition, since the part inside the vehicle is used, the shape of the part to be measured is known, so that the accuracy of distance detection can be improved by taking this into consideration. Therefore, the accuracy of optical axis control can be increased.

  Further, when integrating each distance sensor into the headlamp, there is an advantage that it is not necessary to install each distance sensor individually inside the vehicle, and it is not necessary to secure an installation space and to route a cable.

  Further, since each distance sensor is installed inside the vehicle, there is an advantage that an inexpensive distance sensor using infrared rays or the like can be used.

  In addition, since the measurement target surface for each distance is known and can be kept in a constant state, the tilt angle can be obtained by a method such as simple calculation or data table reference, and the development of an operation program is easy. .

  In addition, this invention is not limited to the content of embodiment mentioned above, In the range of the summary of this invention, it can change and implement variously. For example, as shown in Tables 1 and 2 above, when the distance change detected by one distance sensor 11A is sufficiently smaller than the distance change detected by the other distance sensor 11B. By replacing the distance to be detected by the distance sensor 11A with a predetermined fixed value, the installation of the distance sensor 11A can be omitted. In this case, the coefficient K1 [deg / mm] may be determined corresponding to the distance detected by the distance sensor 11B, or a data table may be prepared.

DESCRIPTION OF SYMBOLS 10: Control part 11: Distance detection part 11A, 11B: Distance sensor 12: Memory 21: Vehicle body inclination angle determination part 22: Optical axis control amount setting part 23: Optical axis control signal generation part 100: Vehicle 101: Body (vehicle body)
102: Drive system (chassis)
103: Engine

Claims (5)

An apparatus for controlling the optical axis of a headlamp provided in a vehicle having a first part whose inclination with respect to a road surface varies and a second part whose inclination with respect to the road surface hardly varies,
A distance detector that is attached to a predetermined position of the first part of the vehicle and detects a distance from the predetermined position of the second part of the vehicle;
A vehicle body inclination angle determination unit that obtains an inclination angle with respect to the road surface in the front-rear direction of the first portion of the vehicle using the distance detected by the distance detection unit;
An optical axis control amount setting unit for obtaining an optical axis control amount of the headlamp based on the inclination angle obtained by the vehicle body inclination angle determination unit;
An optical axis control signal generation unit that generates a control signal for controlling the optical axis of the headlamp based on the optical axis control amount obtained by the optical axis control amount setting unit;
An optical axis control device for a vehicle headlamp, including: The distance detection unit includes two distance sensors that are spaced apart from each other in the vertical direction, and detects the distance from the predetermined position of the second part of the vehicle by each of the distance sensors.
The vehicle body inclination angle determination unit obtains the inclination angle using two distances detected by each of the two distance sensors;
The optical axis control device for a vehicle headlamp according to claim 1. The two distance sensors are connected to the one distance sensor so that the distance detection direction of the other distance sensor is non-parallel with a predetermined angle with respect to the distance detection direction of the one distance sensor. The distance sensor is relatively tilted,
The optical axis control device for a vehicle headlamp according to claim 2. The distance detection unit has one distance sensor, and the distance sensor detects a distance from the predetermined position of the second part of the vehicle,
The vehicle body inclination angle determination unit obtains the inclination angle using a distance detected by the distance sensor and a predetermined fixed distance.
The optical axis control device for a vehicle headlamp according to claim 1.   A vehicle headlamp system comprising: the optical axis control device according to any one of claims 1 to 4; and a headlamp whose optical axis is controlled by the optical axis control device.

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